


Nagisa's Nightmare

by orphan_account



Series: Nagisa and Korosensei [2]
Category: Assassination Classroom
Genre: Anal Sex, Cock Rings, Dream Sex, Forced Ejaculation, Forced Masturbation, Humiliation, M/M, Medieval punishment, Medieval wooden stocks, Orgasm Delay/Denial, Public Humiliation, Public Nudity, Public Sex, Rough Sex, Teacher-Student Relationship, Verbal Humiliation, Voyeurism
Language: English
Status: Completed
Published: 2019-06-12
Updated: 2019-06-12
Packaged: 2020-05-02 04:08:42
Rating: Explicit
Warnings: Rape/Non-Con, Underage
Chapters: 1
Words: 1,929
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19191565
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: Know those nightmares where you show up to school naked? Well Nagisa has a nightmare that is far worse than that. He get's raped by Koro-sensei in the middle of class!





	Nagisa's Nightmare

**Author's Note:**

  * For [Addict_with_a_gun](https://archiveofourown.org/users/Addict_with_a_gun/gifts).



> Sometimes I think i'm awful then I remember that I've read far worse on this site.

Tucked away in the back of the classroom in the corner, Nagisa is daydreaming during a lecture on polynomials when suddenly he feels something cool and slimy slither up his pant leg and coil around his dick. Gasping, he looks down behind his textbook to see what is the matter. Quietly unzipping his pants and peeking beneath the waistband of his underwear, Nagisa sees a familiar yellow tentacle touching him where it really shouldn't. He glances at the front of the classroom. Koro-sensei briefly catches his eye and has the nerve to wink at Nagisa acting like nothing illicit is happening at all. 

What the heck is Koro-sensei doing to him in the middle of class!? Doesn't he know this kind of thing is illegal?? 

Confused, mortified, and deeply uncomfortable, Nagisa tries to kick Koro-sensei's tentacle away, but the stubborn octopus won't budge. Instead, Koro-sensei begins to pump Nagisa's dick in a painfully slow manner. Nagisa blushes and covers his mouth to stifle a moan. Despite his body's natural reaction, he isn't enjoying this unwarranted attack and wants Koro-sensei to stop immediately. 

Checking to make sure no one notices, Nagisa pulls out his dick and tries to peel away the tentacle. His efforts are in vain as Koro-sensei only tightens his grip and begins to pump him faster. 

An inadvertently loud moan escapes his lips and the entire class whirls around to look at him. 

"What the heck, Nagisa!?" Cries Maehara, who sits right next to him. "Are you jerking off during class?" 

Everyone gasps. 

"I-no!" Nagisa puts his hands up and shakes his head furiously. "This isn't what it looks like! Koro-sensei is touching me!" 

"Touching you!?" Koro-sensei says incredulously. "Never!" 

"It's the truth!" Nagisa looks down again but Koro-sensei's tentacle is no where near him. All he sees is his own dick half hard and out in the open. He hastily covers his crotch with his hands in sinks in his seat. 

"My, my. I never pegged you for a liar, Nagisa-kun." Koro-sensei tuts. "And I certainly never thought you would do such a perverted thing in the middle of class!" 

"Yeah, I always thought it would be Okajima we'd catch jerking off." Karma smirks. 

"Hey!" Okajima scowls. "I have the decency to jerk off in private, thank you very much!" He huffs and crosses his arms. "I'm not like a certain someone hiding in the back row!" 

Koro-sensei shakes his head solemnly. "Nagisa-kun, for lying and exposing yourself in public, I have to severely punish you." 

Without warning Koro-sensei's tentacles shoot across the classroom, wrap around Nagisa, and force him to the front of the classroom. 

"Since you like exposing yourself, why not take off your clothes?" In mach speed Koro-sensei removes Nagisa's clothes and tosses them into the trash bin. Nagisa is frozen in place completely in shock. The rest of class 3-E begins to snicker and mutter to themselves. 

"Look at him, how shameful." Whispers one of the girls.

"Wow, so Nagisa really is a boy." Whispers on of the guys. 

"Hm," Koro-sensei pokes at Nagisa's half hard dick. "Why don't you go ahead and finish what you started?" 

"Wh-what?" Nagisa starts to tremble.

"Go on," Koro-sensei urges. "Before I think of a worse punishment." 

Tentatively, Nagisa wraps his hand around his dick. The entire class holds their breath. As Nagisa begins to pump himself slowly, they begin to laugh. 

"I can't believe he's really doing it!" Nakamura shrieks.

"Unbelievable!" Ritsu says, starting to record the spectacle. 

Hot tears burn in Nagisa's eyes. "Please, Koro-sensei. Just give me detention!" 

"Too late." Koro-sensei sneers. 

The class continues to laugh and once Nagisa brings himself to orgasm shooting his seed onto the floor they only laugh harder and fall out of their seats. Thinking that his punishment is over, Nagisa makes to grab his clothing from the trash bin. 

"Not so fast, Nagisa-kun." Koro-sensei pulls him away. "We aren't done yet. I think the class is overdue for a lecture on sex education. You can be my assistant." 

"Huh!?" 

Suddenly Koro-sensei has Nagisa's hands tied behind his back. Removing Nagisa's hair ties, he places them around the base of his dick as a makeshift cock ring. Nagisa shivers as his hair brushes his shoulders. 

"Alright class!" Koro-sensei calls out and the students straighten themselves out and stare at him attentively. "Time to begin our next lesson!" 

Nagisa whimpers as Koro-sensei strokes his face. "Nagisa-kun has gladly volunteered to be my assistant. We'll use him to demonstrate how to properly be fucked like the perverted loser he is." 

The students begin to snicker again. Koro-sensei waves for them to gather around and they congregate around him and Nagisa in a half circle. No one has a bad view of the show about to go down. 

"Pay close attention now. I'll begin by stretching his ass wide enough to be able to take my penis." With that, Koro-sensei shoves his tentacles up Nagisa's ass and begins to pry his tight entrance open. "While we do this, let's tease him." Koro-sensei's tentacles slither up Nagisa's slim body and begin to caress his chest and pinch his perky nipples. Another tentacle wraps around his dick and starts pumping him again while simultaneously squeezing his balls. 

Nagisa begins to moan as his tears overflow and sluice down his cheeks. His dick hardens and begins to leak pre-cum.

"I think he's enjoying it!" Kayano gaps. "He's so perverted!" 

Okuda points at Nagisa's crotch. "His dick is hard again too!" 

The classroom erupts in laughter again. 

Koro-sensei finally releases Nagisa's dick, now completely erect and flapping about wildly, and slides his tentacles out of his ass. "I think Nagisa's ready for my penis now. Terasaka-kun, please reach into the top drawer of my desk and hand me the lube."

Terasaka obliges and tosses Koro-sensei the lube. Koro-sensei then pours half the bottle down Nagisa's crack and spreads his butt cheeks as far apart as they can go. Nagisa squirms and struggles to break free of Koro-sensei's tentacles wrapped around his body. 

"Please, sensei! Don't do this!" He begs breathlessly. Koro-sensei only grins. 

"Fuck him! Fuck him!" The class chants. 

Koro-sensei shoves himself inside Nagisa eliciting a yelp from the boy and a cheer from the class. "Don't worry, if you relax it won't hurt at all." Nagisa whimpers again and struggles harder. The feeling of Koro-sensei inside him is unusual. His dick is large and thick and feels like it reaches his stomach! Despite the amount of pain he's in, the strange sensation of being full is also pleasurable and Nagisa curses himself for thinking that he might enjoy the feeling of Koro-sensei's dick rubbing against his walls and growing larger inside him. 

Koro-sensei begins to thrust into Nagisa in mach speed. No point going easy on a student being punished. Within seconds Nagisa is howling and moaning like crazy as tears splash onto the floor mixing with the drops of pre-cum leaking from his bouncing dick. 

"Sensei stop! Ah! Sensei!" Nagisa screams. "That's too rough!" 

"Nothing less for a pervert." Koro-sensei shrugs and fucks him harder. 

Koro-sensei continues to fuck while his classmates laugh for what feels like hours to the suffering Nagisa. Soon, the unfortunate boy can't take the feeling of his dick begging to release once again. 

"Sensei! I need to cum!" 

"Tsk, you can't cum until you admit to being a slut." Says Koro-sensei smugly. 

"Sensei!" Nagisa cries, not willing to lose whatever dignity he still has. He's not sure how, but Koro-sensei manages to fuck him even harder! Lost in pain, all Nagisa can hear now are the sounds of his screaming and moaning and Koro-sensei's balls slapping his skin. He can't hear his classmates mocking laughter anymore. 

"Will you admit that you're a slut, Nagisa-kun?" Koro-sensei wraps a tentacle around his dick again. "This will all be over once you admit it."

Nagisa grits his teeth. His engorged cock can't handle it anymore. 

"I-I'm...." 

"Go on." 

"I'm-I'm a slut!" Nagisa shouts. "I'm a dirty cock loving slut!" 

The class goes wild. 

Grinning evilly Koro-sensei free's Nagisa's dick allowing the boy to shoot his seed across the classroom. Nagisa continues to cum over and over again nonstop as Koro-sensei keeps thrusting until he reaches his own climax and cums inside of him coating his walls with his seed. Koro-sensei pulls out and let's the boy fall to the ground in a messy heap trembling. Lube and semen drip down his thighs. 

His ass feels sore and his legs are weak. At the very least his limp dick finally feels relief. 

"Excellent job, Nagisa-kun." Koro-sensei leers over him. "But for admitting that you're a slut, I'll have to punish you again!" 

In the blink of an eye Nagisa is trapped in medieval wood stocks still naked and on the gymnasium stage in front of the entire school. 

"What's going on!?" Nagisa gapes. 

"As punishment for being a slut, the entire male population of the school is free to fuck you whenever they please." Koro-sensei explains. "Would you look at that, there's already a line forming." 

Behind Nagisa's exposed ass is a line of male students all waiting to fuck him that wraps around the gymnasium three times and goes out of the building. 

"No! No!" Nagisa struggles to break free. "Haven't I been punished enough?! I didn't even do anything wrong!" Nagisa flinches at the sound of the first male student unzipping his pants and gasps when his hands grab his butt cheeks and spread them wide. The tip of the student's dick rubs teasingly along Nagisa's crack and the imprisoned boy whimpers. 

"Sensei!" He cries out as the male student shoves into him. 

"Have fun, Nagisa-kun!" Koro-sensei waves and disappears. 

_"Sensei!"_

____

____

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

Nagisa jolts awake panting in a cold sweat. He reaches for the bedside table and flicks on the lamp. He looks at the clock. It's 3am in the morning and still dark outside. 

Once he's calmed himself down, he frowns noticing that his horrible wet dream had made him ejaculate onto his bed sheets. Kicking them off, he shivers as the cool night air tickles his exposed skin. Wait a second, why did he fall asleep naked? And this wasn't his bedroom either. All over the walls were cutouts from porn magazines. 

"Bad dream?" Koro-sensei walks into the room holding the porn magazine he had been reading just moments ago. 

Nagisa blinks as it all comes back to him. A month ago he had promised to be Koro-sensei's slut after a wonderful sex session during his first detention. His dream of being his teacher's pet had literally come true that day and he's been having sex with Koro-sensei almost every day and night since then. 

"Yes," Nagisa admits. "I-I dreamt that you raped me in the middle of class!" 

Koro-sensei raises an eyebrow. "Oh?" 

"It was horrible!" Nagisa continues. "I can't believe I _hated you _for fucking me!"__

____

____

Koro-sensei laughs. "It was just a dream. They can be weird sometimes." 

"That's not even the worst part! In the dream, you allowed other people to fuck me!" 

"Don't worry, that will never happen. You're my slut." Koro-sensei crosses the room and caresses Nagisa's cheek. "You know that you'll always be mine and mine alone to fuck." He pushes Nagisa down gently on the bed and spreads the boy's legs wide. 

Nagisa nods, positioning himself so he's comfortable. "I know." 

Koro-sensei tickles the boy's ass."Now what do you say we have a little fun to make you forget your nightmare?" 

Smiling, Nagisa spreads his legs wider. "Yes, sensei."

**Author's Note:**

> Doesn't change the fact that i'm despicable though.


End file.
